Wednesday, February 25, 2009

1999 Buick Regal climate control problem . When I started, A/C unit hot air comes out on one side and cold on the other side and now 1 week later the heater or A/C are not working.

Answer:

2 things that can cause this problem. A low refrigerant level in the A/C system can make the passenger side colder than the drivers side. Until all the refrigerant leaked out and now the A/C isn't working at all. You will need to get the refrigerant level checked in the system to determine this.The other thing is the control head for the A/C unit. GM has a bulletin for this. # 02-01-39-001. I have added the TSB below. To tell if this is the problem, You would need to get the codes checked in the HVAC module. and see if the scan tool can control the temperature doors.

#02-01-39-001: HVAC Temperature Difference Side to Side and/or DTC B0361, B0441 Set (Replace
HVAC Controller, Splice into Backlighting Circuit) - (Feb 7, 2002)
Subject: HVAC Temperature Difference Side to Side and/or DTC B0361, B0441
Set (Replace HVAC Controller, Splice into Backlighting Circuit)
Models: 1997-99 Buick Century, Regal
1998-99 Oldsmobile Intrigue
with RPO CJ2
Condition
Some customers may comment on a temperature variation between the left and right hand ducts.
Typical concerns may include that the right side of the vehicle cools down but the left stays warm or
the opposite. This condition is sometimes associated by the customer with a recent service visit for
other non-related repairs. The codes, DTC B0361 or B0441, may be present but will not illuminate a
telltale lamp.
Cause
The HVAC controller unit and the TEMP door actuator motors rely on a feedback system that supplies
the controller with count values in order to accurately adjust the air temperature. When battery power is
interrupted to the HVAC controller, the current actuator position values are lost. When power is
restored, the controller will perform a "sweep test" of the doors from full cold to full hot and record the
end values for reference. Over time, the TEMP doors may develop some flexing when run to their
extremes. This flexing allows the count values to run out of range (beyond 0-255) and results in DTC
code B0361 or B0441 to set.
Correction
A revised HVAC controller has been released with new programming that allows for a wider tolerance
in the expected range of the TEMP door. Replace the controller using the procedure below:
Important: On the 1997 Buick Century and Regal, additional steps are required. You will have to run a
jumper wire to the new HVAC controller. Be sure to follow the additional 1997 model year steps below.
1. Disconnect the negative battery cable.
Important: On the Buick Regal, the console must first be removed to access the HVAC
controller. For Buick Century and Oldsmobile Intrigue, skip to Step 10.
2. Apply the parking brake and block wheels.
3. Shift the transmission to first gear.
4. Remove the console trim plate and disconnect the electrical harness.
5. Disconnect the cigarette lighter sockets.
6. Remove the console storage box.
7. Remove the console control plate and disconnect electrical harness for traction control and
heated seats, if equipped.
8. Remove the console retaining bolts.
9. Remove the console from the vehicle.
10.Remove the HVAC trim panel, if equipped.
11.Remove the HVAC controller retaining bolts.
12.Disconnect the electrical harness.
13.Discard the HVAC controller.
Important: At this point, you must refer to the 1997 Buick section below if working on that
model and year. The section below includes steps to revise vehicle wiring to enable HVAC
controller backlighting.
14.If the vehicle is a 1997 Buick Century or Regal, refer to the section below titled 1997 Buicks
(Enabling Backlighting Circuit).
15.Connect the HVAC controller electrical harness and install the controller retaining bolts.
16.Install the control module trim plate, if equipped. Skip to Step 23 for the Buick Century and
Oldsmobile Intrigue. Continue below for the Buick Regal.
17.Install the console to the vehicle.
18.Install the console retaining bolts.
19.Install the console control plate and connect the electrical harness for traction control and
heated seats, if equipped.
20.Install the console storage box.
21.Connect the cigarette lighter sockets.
22.Install the console trim plate and connect the electrical harness.
23.Shift the transmission to PARK and unblock the wheels.
24.Connect the negative battery cable.
Additional Steps for 1997 Buicks (Enabling Backlighting Circuit)
1. Remove the radio retaining bolts.
2. Remove the radio and disconnect the electrical harness.
3. Prepare an 457.2 mm (18 in) long, 18 gauge jumper wire. If multiple colors are available, it
would be the most convenient to use grey to continue the backlighting circuit in the same color.
4. Locate and splice one end of the jumper wire to the grey wire occupying pin location F4 at the
radio harness.
5. Position the radio back into the I/P and route the jumper wire down to the HVAC controller
harness location.
6. Using a new terminal (GM P/N 12146447 Micro-Pak .35-.50), attach and install the other end
of the jumper wire into cavity C16 of the HVAC controller harness. The row and column
position indications are molded into the body of the HVAC controller at the harness location.
7. Connect the electrical harness to the HVAC controller.
8. Connect the negative battery cable and test the HVAC backlighting by turning on the headlamps
and varying the backlighting intensity.
9. Install the radio retaining bolts.
10.Install the I/P upper trim panel.
11.Refer back to Step 15 of the Correction section to complete the procedure. (You will have
already connected the electrical harness).

Parts Information
Part Number Description
10435588 Controller, HVAC (Buick)
9388139 Controller, HVAC (Oldsmobile)
Parts are currently available from GMSPO.

23 comments:

Keep it simple: simply dissconect the battery at the coldest temperature (night time). The AC doors then shut based on the outside temperature. Wait a few hours (if you have run the engine) and then reconnect the battery. This will fix the problem. If you live in AZ it will work better than before, but if it was 75 degrees out you still might have a bit of problem.

well i was searching for this type of info since when i faced this problem last sunday and now i have found it. i don't get enough time on net to search the internet because of my job but thanks to you guys. :)